Portable gound fault interrupter apparatus

ABSTRACT

A housing and component mounting assembly is described for a hand-portable ground fault interrupter apparatus. The housing comprises a base member and a cover member which includes a readily demountable electric receptacle plate. The components are arranged for compartmentizing the housing. The described arrangement enhances portability and receptacle replacement as well as increasing protection from electrical shock hazards.

United States Patent Carlson et al.

1451 May 16, 1972 [54] PORTABLE GOUND FAULT 2,388,054 10/1945 l-lartzell..320/2 x INTERRUPTER APPARATUS 2,662,110 12/1953 Fiori ....339/106 R1,929,218 10/1933 Sambleson. ..220/3.94 I 1 lnvemors= Ernest Carlson,Fairfield; Czeslaw 3,120,414 2/1964 Farish ..174/66 R ac Trumbull; PaulMirmina, 2,988,655 6/1961 Rudolph etal ..200/51 LM ux M1lf0rd,all0fC9nn-2,625,591 1 1953 George ..317 99 R 2,590,805 3/1952 Vitale........307/150 R [73] Ass'gnee lm'pmted Bndgepm' 3,159,436 12/1964 Davis..174/52 x [22] Filed: Apr. 15, 1970 FOREIGN PATENTS OR APPLICATIONS[21] A p1.No.: 28,576 162,943 4/1954 Australia ..317/18 B UX PrimaryExaminerDavid Smith, Jr. [52] U.S. Cl ..317/101 DH, 174/52 R, 200/51 R,Anomey wooster, Davis & Cif ||i 307/150 [51] Int. Cl. ..H02b l/02 [57]ABSTRACT [58] Field ofSeai-ch ..317/101 DH, 101 LL, 101 C,

317/] R, 99 18; 220/394, 4; l74/52 R, 53 R, 66; A housing and componentmounting assembly is described for 307/94, 1 l 4 150 10R; 320/2; 334/166R; 20051 ahand-portable ground fault interrupter apparatus. The hous- Mmg comprises a base member and a cover member which includes a readilydemountable electric receptacle plate. The components are arranged forcompartmentizing the housing. [56] References Clted The describedarrangement enhances portability and recepta- UNITED STATES PATENTS clereplacement as well as increasing protection from electrical shockhazards. 3,471,706 10/1969 Schneider ..307/10 R 2,887,525 5/1959 Lewus 174/52 R 12 Claims, 12 Drawing Figures 34 66 65 I r Q Willi- Fun. I, r47l j II U I LIFT 1 I ill: 1-" I! Q I I 1 W I '32 I F s 1 2.7 g 5 y 26 m!"W M 25 0 t 1 My 3] 11... R Q 42 I11 m K 1B 45 11 i In 125 25 k 30 I I t7p 4.9

Patented May 16, 1972 5 Sheets-Sheet w 6 M 0 a d u 6 ad ua 56 PORTABLEGOUND FAULT INTERRUPTER APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates to apparatus for automatically interrupting theapplication of electrical power to a device upon the occurrence of aground circuit fault. The invention relates more particularly to theprovision of an improved hand-portable ground fault interrupting (GFI)apparatus.

In various electrical systems, a ground circuit is established betweenan electrical utility device and a source of electrical power for thedevice. One purpose in providing the ground circuit is to eliminatepossible electrical shock hazards if, for example, an insulation defectoccurs in the utility device. The elimination of a shock hazard isparticularly important in applications where personnel have occasion tofrequently come into physical contact with the utility device. This canoccur in hospital applications, for example, wherein the device maycomprise an analytical or administrative instrument and patients arenormally brought into physical contact with conductive members of thedevice. While a ground circuit can be readily provided through the useof grounded conductors in the power source, its distribution system andin ground leads in thepower cable for the utility device, various faultscan occur in this ground circuit. An undesirable result then is thecreation of an apparently safe and grounded, yet potentially defectiveand hazardous, condition.

GFI apparatus have been provided in order to eliminate the electricshock hazard when a fault in a ground circuit does occur. A GFIapparatus is adapted for coupling electrical power from the source tothe device and for automatically interrupting this coupling upon theoccurrence of a ground circuit fault. The GFI apparatus includes acircuit arrangement for sensing the electrical condition of the groundcircuit and for operating a circuit-breaking element which interruptsthe application of electrical power to the device when a fault conditionisindicated. Ground fault interrupting circuits are known and aredescribed in detail, for example, in U.S. Pat. No. 3,473,091, Morris andMcDonald, entitled Ground Leakage Differential Protective Apparatus,assigned to the assignee of this application.

In institutional, industrial and office uses, a large number of devicescan derive electrical operating power from any of a great number ofservice outlets distributed throughout a building or office area. Theprovision of GFI apparatus at each outlet or even at each device thenbecomes prohibitively expensive. It is preferable to provide a GFIapparatus which can be utilized at a number of different locations.

It is an object of this invention to provide an improved form of GP Iapparatus which may be transported and utilized at different locations.

Another object of the invention is to provide an improved hand-portableGFI apparatus.

Another object of the invention is to provide an improved, portable,multi-receptacle, GFI apparatus which can simultaneously supply theoperating electrical power requirements for a plurality of utilitydevices.

Another object of the invention is to provide a portable GFI apparatuswhich eliminates potential shock hazards from the GFI apparatus itself.

A further object of the invention is to provide a GFI apparatus adaptedfor readily substituting various forms of receptacles in the apparatus.

Another object of the invention is to provide an improved form oftwo-piece handle having a non-slipping grip for facilitating transportof apparatus from location to location.

Still another object of the invention is to provide an improved powercable clamp for electrical apparatus.

Another object of the invention is to provide an improved,compartmentized housing arrangement for an electrical apparatus.

Another object of the invention is the provision of a compartmentizedhousing arrangement for electrical apparatus having access to powercable terminals for replacing the power cable while isolating otherportions of the apparatus from the user.

These and other objects and features of the invention will becomeapparent from the following specifications and the drawings, wherein:

FIG. 1 is a perspective view of a GFI apparatus constructed inaccordance with features of this invention;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is a side view of the apparatus of FIG. 2;

FIG. 4 is a sectional view of the apparatus taken along lines 4-4 ofFIG. 2;

FIG. 5 is a bottom view of the apparatus of FIG. 3, partly cut away forillustrating the location and mounting of various electrical components;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 4 forillustrating a multi-receptacle array employed in the GFI apparatus;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 4 illustratingthe mounting and positioning of a pilot light, a test pushbutton, and acircuit breaker of the GFI apparatus;

FIG. 8 is a sectional view taken along lines 8-8 of FIG. 4, partly cutaway, illustrating the compartmentization of the apparatus housing aswell as the mounting and positioning of various electrical components;

FIG. 9 is a sectional view taken along line 99 of FIG. 4 illustrating acable clamp feature of the invention;

FIG. 10 is a partial front view of a receptacle plate of the apparatusillustrating a receptacle mounted thereto;

FIG. 11 is a sectional view taken along the line 11-11 of FIG. 10illustrating the mounting of a receptacle to the plate and a shockhazard insulator arrangement for the plate; and,

FIG. 12 is a perspective view of a grounding bar utilized for providinga common electrical ground conductor for receptacles mounted to thereceptacle plate of FIG. 10.

Referring now to the drawings and particularly to FIGS. 1 5, a GFIapparatus is shown to include a housing which comprises a cover memberreferenced generally as 20, a base member 21, and a demountablereceptacle plate 22. The cover member 20 which is formed as athin-walled body of electrically insulative material includesan uppersurface 23 having relatively planar segments, and an integral wallsegment 24. The wall segment 24 which extends away from the surface 23at the periphery of this surface also extends discontinuously above theperiphery. The demountable receptacle plate 22 which is also formed ofan electrically insulative material as a thin-walled body is positionedin a cap of-the wall segment 24 of the cover member 20. This demountableplate is secured in place in the cover member 20 by the base member 21which is similarly formed as a thin-walled body of electricallyinsulative material. As indicated in detail hereinafter, the base member21 is demountably secured to the cover 20.

The receptacle plate 22 includes a plurality of electric receptacles 25,each shown to be of a standard two-pronged type having a ground terminalpin. A utility device to which electrical power is coupled will includea plug having a twopronged arrangement and a ground terminal for matingwith the receptacles 25. Electrical receptacles of other designs, suchas a standard two-pronged type may also be used depending on the wiringarrangements of the energy source and the equipment to be used.Electrical power is supplied to the GFI apparatus for coupling to autility device at a receptacle 25 through a power cable 26. The powercable 26 which also includes a two-pronged plug 27 having a groundingterminal pin 28 enters the apparatus housing through an aperture 38located in a rear section of the wall 24.

The apparatus is hand-portable and is readily transportable fromlocation to location by a carrying handle 29 which is integrally moldedto the cover member 20. The handle extends from the wall 24 in a forwarddirection about the receptacle plate 22. The handle 29 includes anintegral elongated transverse segment 30 having an arrow-shaped crosssection which receives a handle gripping body 31. The gripping body 31includes an elongated groove having an arrow-shaped cross section whichis adapted to mate with the arrow-shaped cross section of the transversesegment 30 and is thereby securely mounted to this segment.

The thin-walled, electrically insulative cover, base and receptacleplate of the housing in a typical but non-limiting arrangement areformed of molded LEXAN polycarbonate having a nominal thickness of 0.080inch, for example. The housing is therefore constructed of a ruggedmaterial which exhibits a high impact force characteristic. The grippingmember 31 is formed, for example, of extruded polyvinyl chloride whichprovides a substantially non-slip surface for gripping the apparatus.

In operation, the illustrated GFI apparatus is energized by insertingthe power cable plug 27 into a power outlet receptacle which provides,for example, a 115 volt, A.C. 60 cycle potential and by advancing anoperative lever 32 of a circuit breaker to its foremost position, asillustrated in FIG. 2. In the absence of a ground fault, the GFIapparatus is adapted to then cause a pilot light 34 to glow and indicatethat power is being applied to the apparatus. The operativeness ofcircuit components internally positioned in the housing for interruptingthe application of electrical power to a utility device, is determinedinitially by depressing a test pushbutton 36. The operation of thepushbutton 36 and its associated circuitry causes an apparent groundcircuit fault to exist. The circuit breaker thus trips and the lever arm32 returns to a rearmost position. Electrical power to the receptacles25 is thereby interrupted and the pilot lamp 34 is simultaneouslyextinguished.

A more detailed description of the GFI apparatus housing and assemblywill now be given, particularly with respect to FIGS. 4 12. The powercable 26 extends through an aperture 38 in a rear segment of the wall 24and is securely gripped by a cable clamp which includes a semicircularseat formed by a plurality of ribs 40 integrally molded in the covermember 20. A nylon clamp member 42 includes ribs corresponding to thoseof member 40 formed in a semicircular configuration for seating againstthe cable 22 which is laid between these members. As best seen in FIG.9, the clamp members include symmetrically located holes through whichscrews 43 extend. These screws engage the internally threaded holes ofclamp member 40. The cord clamping arrangement thus features arelatively simple yet rugged, inexpensive, and double insulating cordgripping facility.

The wall segment 24 of the cover 20 includes channels integrally formedon an inner surface thereof for spacing and supporting circuit boards.The circuit boards are positioned generally parallel to the receptacleplate 22 and compartmentize the housing. A first circuit board 44 (FIG.comprises a terminal circuit board having feed-through terminalconnectors 45, 46 and 47 thereon and extending through the board. Theseterminals provide a conductive connection between a power cablecompartment 48 formed by the circuit board 44, the cover 20, and housingbase member 21. The circuit board 44 is positioned in integrally moldedchannels 49 of the cover 20. One wire of the power cable 26 is connected(not illustrated) to the terminal 45, a second wire is connected (notillustrated) to the terminal 46, while a ground wire of the cable 26 isled (not illustrated) through a slot 54 in a shoulder 56 to the terminal47. A second shoulder 58 is provided which along with the shoulder 56assures rigidity of the circuit board in its extension across the covermember between the channels 49. These shoulders, which are integral withthe upper surface 23, also function to prevent the possibility ofuninsulated end segments of the cable at the terminals from coming intophysical contact and thereby causing a short circuit. The housing basemember 21 is shown to comprise a two-piece assembly including a plate 59which forms a closure member for the compartment 48. The plate 59 issecured by a pair of screws 60 extending through apertures in this plateinto internally threaded bosses 61 which are integrally molded on theinner surface of the cover 20. The plate 59 further includes a lip at aforward edge 62 thereof extending under an edge of a flanged segment ofa second plate 63 of the housing base member 21.

A second compartment 64 for the apparatus is formed by the circuit board44 and by a second circuit board 65. The board 65 is similarlypositioned within the cover 20 by channels 66 which are integrallyformed in the cover. Circuit board 65 includes circuit componentsmounted thereon which form a portion of the circuit arrangement forsensing the condition of the ground circuit. The second compartment 64includes a differential transformer toroid 70 which is shielded fromexternal magnetic fields by a cylindrically shaped magnetic shield 72.The toroid and shield are secured in place by a disc 74 formed of aninsulating material. The disc is forced against the toroid and shield(FIG. 8) by a screw 76 extending through an aperture in the disc andengaging an internally threaded boss 78 which is integrally formed inthe cover 20. A second toroid 80 is also positioned in this compartmentand is mounted in a similar manner.

A third compartment 82 is formed by the circuit board 65 along with thereceptacle mounting plate 22 and the cover 20. This compartment housescomponents which are mounted to the surface 23. These components includea circuit breaker 84, a transformer 86, the pilot light assembly 34, anda test pushbutton assembly 36. The various detailed circuitinterconnections between these elements is not illustrated for purposeof clarity in the drawings. The circuit breaker 84 is mounted to thesurface 23 by screws 87 which extend through the surface 23 at arecessed section and engage the circuit breaker body. In a similarmanner, the transformer 86 is mounted by screws 88 extending through ametal core clamp for the transformer and engaging integrally formedbosses extending from an inner surface of the cover 20. The latterscrews do not, therefore, extend through the surface 12. As illustratedin FIG. 7, both the test pushbutton 36 and the pilot light 34, each ofwhich have housings formed of an electrically nonconductive material,include integral resilient tabs 90 and 92, respectively, which extendfrom and engage an inner surface of body 20 and secure these electricalelements to the body 20.

The receptacle mounting plate 22 is shown to include a plurality ofhorizontally positioned and aligned receptacles 25 mounted on the plate.The means for mounting the receptacles is illustrated clearly in FIGS. 4and 11. The plate 22, which, as stated hereinbefore, is formed of anelectrically nonconductive material, includes a generally flat surfacehaving tapered flanged end segments 94. Apertures are formed in theplate 22 for introducing a plug to a receptacle. The receptacles 25 aremounted to the plate 22 by screws 96 which extend through the plate 22from an outer surface thereof and engage threaded apertures in a metalyoke strap 97 of each receptacle. In order to provide a hazard-freeelectrically non-conductive surface, these screws and the receptacleplate are covered by a relatively thin polycarbonate plastic plate 98which is secured to the plate 22 by conventional ultrasonic mechanicalbonding techniques. In particular, the insulating plate is bonded to thereceptacle plate 22 by the use of an annular energy director ring whichis positioned about each receptacle aperture during the bonding process.Each of the receptacles 25 includes a screw 100 which engages a threadedaperture in the associated metal yoke strap 97. The strap 97 which iselectrically conductive is conductively connected to a ground pin 102 ofeach receptacle. Common grounding of each of the receptacles is achievedby an elongated grounding bar 104 (FIG. 12) which is formed ofelectrically conductive material. The bar 104 is of generallyrectangular cross section and includes spaced slots 106 for receivingthe grounding screws 100 of associated receptacles. The grounding barfurther includes an integral male stab terminal 108 flanging upwardly atan extremity thereof. This terminal 108 advantageously provides aquick-connect facility for the apparatus.

The receptacle plate assembly is slidably positioned in a tapered groove110 which is integrally formed in an inner surface of the cover 20. Thegroove is formed in the cover 20in a manner for providing that anexternal surface of the plate 22 is positioned in a plane inclined withrespect to a vertical plane through the apparatus. Because of thisinclination, the user of the apparatus has greater facility for viewingand inserting the power cable plug of a utility device into either ofthe receptacles. Furthermore, in view of the alignment of thereceptacles in a single row, there is little likelihood that powercables for various utility devices will become entangled.

An inner shoulder 118 is formed in an edge of an integrally formedflange segment 119 of the plate 63. The cover member 20 is assembled onthe plate 63 and a lower edge of wall 24 nests on shoulder 118.

The plate 63 includes a groove 120 which receives a lip or extendingtongue segment 122 at an edge of the plate 22 and secures the receptacleplate in the body 20. The plate 63 further includes bosses 124 which areintegrally molded in the plate and which are positioned for abuttingagainst the circuit board 65 in order to secure this circuit board inplace. The plate 63 is secured to the cover body 20 by screws 126 whichextend through the plate and engage internally threaded integrallymolded bosses 128. The bosses 128 are elongated and extend from thesurface 23. Apertured metal caps 130 are press fitted to the ends ofbosses 128 for protecting the entrance thread of the boss. The screws126 extend through bosses 132 integrally formed in the plate 21. Thesebosses include a recessed segment for shielding the screw head fromphysical contact with a user. In addition, these bosses include skirtsegments 134 which surround the caps 130 and, therefore, shield themfrom any possible contact with electrical elements or wiring within theapparatus. A skirt 136 is also integrally molded in the plate 22 forsurrounding an internally exposed head of the hold-down screw of thedifferential transformer 70. The screws 126 comprise tamper-proof screwsinhibiting ready removal of plate 63 by a user of the apparatus. Accessto the second and third compartments of the apparatus is thus limited totrained personnel. Additionally, this is a protective measure in orderto protect the user from injury by electrical shock. Support feet 138are resilient and secured to the plate 63 and support the apparatus on asurface in a generally horizontal position. The plate 59, however, isremovable for replacement of the line cord should it become frayed orworn. This replacement, however, will not expose the second and thirdcompartments and assures that no components will be tampered with.

When desired, the receptacle plate 22 can be removed for replacement orsubstitution of receptacles of different types. Removal of the plate 22,of course, requires removal of the lower plate 63 and the ability toremove the tamperproof screws.

A readily portable and relatively rugged ground fault interrupterapparatus has thus been described. The apparatus advantageouslycomprises the assembly of electrical components in a novel housingfeaturing compartmentization, a demountable receptacle plate forfacilitating substitution of receptacles, a novel cable grippingarrangement and carrying handle arrangements, as well as featuresassuring elimination of shock hazard or providing facilities forreplacing the cable.

While we have described a particular form of our invention, it will beunderstood that various modifications may be made by those skilled inthe art without departing from the scope of the appended claims and thespirit of this invention.

We claim:

1. In an electrical apparatus for interrupting the coupling ofelectrical power between a source of power and a utility device upon theoccurrence of a fault in a ground circuit, an improved portable housingarrangement for the apparatus comprising:

a thin-walled cover body formed of electrically insulative material,said cover body having an upper surface and an integral wall segmentextending away from and discontinuously about the periphery of thesurface;

said. body including means for receiving a demountable receptacle platein an aligned position;

a generally flat, thin-walled, demountable electrical receptaclemounting plate positioned in alignment with said cover body and formingwith said wall segment a continuous four-sided wall for the apparatus,one side formed by said receptacle plate and a side opposite saidreceptacle plate including an aperture for receiving a power supplycable;

a generally flat, thin-walled electrically insulative base means formedof at least two generally flat members for supporting said body on asurface and for forming with said body an enclosure for components of acircuit arrangement for the apparatus; and

a plurality of flat circuit boards formed of electrically insulativematerial supported within said housing in a direction parallel to saidreceptacle plate by members integrally molded in said cover body andforming with said cover body, said receptacle plate and said base meansa plurality of compartments,

one of said flat support plate members forming a closure for one of saidplurality of compartments formed by one of said circuit boards and saidwall segment including said apertured side.

2. The apparatus of claim 1 wherein said one of said circuit boardsincludes a plurality of feed-through terminals for receiving conductorsof a power cable.

3. The apparatus of claim 1 including an electrical power supply inputcable clamp comprising first and second semicircular segments having aplurality of semicircular ribs adapted to grip an electrical powersupply input cable transversely at a plurality of axially spaced pointsand said first segment is integrally molded in said cover body or basemeans.

4. The apparatus of claim 3 wherein said integrally molded segment ismolded in said cover body. 7

5. The apparatus of claim 1 wherein said receptacle plate includes aplurality of receptacle apertures, a plurality of receptacles mountedthereto at associated apertures by electrically conductive means, and athin-walled insulative body positioned at an outer exposed surface ofthe plate and bonded thereto near each of said receptacle apertures.

6. The apparatus of claim 1 wherein said receptacle plate is positionedin a plane inclined with respect to said base means and includes aplurality of receptacles mounted thereon, all of said receptacles beingaligned in a single direction on said plate.

7. The apparatus of claim 6 wherein said receptacle plate includestapered flanges at opposite extremities thereof and a tongue segment atone edge thereof, said cover body includes integrally molded taperedgrooves for receiving said flanges and said base means includes a groovefor receiving said tongue segment for securing said receptacle plate.

8. The apparatus of claim 1 including a two-piece transport handle, saidhandle comprising a first member integrally molded to said cover body,said molded handle member having a pair of segments extending generallynormally away from said wall and a transverse segment extending betweensaid normal segments, and an elongated gripping member positioned onsaid transverse segment.

9. The apparatus of claim 8 wherein said transverse handle segment has across section which is generally arrow-shaped and said gripping memberincludes a groove having a cross section formed for receiving said arrowshaped transverse segment.

10. The apparatus of claim 6 including a flat, linear, elongated groundbar of generally rectangular cross section which is formed of anelectrically conductive material, said bar including a plurality ofslots formed in the cross section along its length for receiving agrounding screw of a receptacle to thereby provide a common groundingbar for a plurality of receptacles, said ground bar including a flangedsegment at an extremity thereof, thereby forming a male terminal forengaging a female connector.

11. In an electrical apparatus for interrupting the coupling ofelectrical power between a source of power and a utility device upon theoccurrence of a fault in a ground circuit, an improved portable housingarrangement for the apparatus comprising;

a thin-walled cover body formed of electrically insulative material,said cover body having an upper surface and an integral wall segmentextending away from and discontinuously about the periphery of thesurface;

said body including means for receiving a demountable receptacle platein an aligned position;

a generally flat, thin-walled, demountable electrical receptaclemounting plate positioned in alignment with said cover body and formingwith said wall segment a continuous wall for the apparatus;

a generally flat, thin-walled electrically insulative base means forsupporting said body on a surface and for forming with said body anenclosure for components of a circuit arrangement for the apparatus;

said cover body including a plurality of linear, elongated, in-

tegrally molded bosses extending from the upper surface in a directiongenerally perpendicular to said upper surface and for a distancesubstantially equal to a width of said wall, said bosses includingrecesses formed therein for receiving a mounting member, and said basemeans includes apertures formed therein through which a mounting memberextends for securing said base means to said cover body; and

circuit mounting means supported within said housing and forming withsaid cover body, said receptacle plate and said base means a pluralityof compartments.

12. The apparatus of claim 11 including an apertured cap of electricallyconductive material positioned on an extremity of said boss forintroducing a mounting member to the recess of said boss, and anintegrally molded skirt formed in said insulative support base means,co-aligned with said boss, and extending a distance away from saidsupport base means for shielding said cap.

1. In an electrical apparatus for interrupting the coupling ofelectrical power between a source of power and a utility device upon theoccurrence of a fault in a ground circuit, an improved portable housingarrangement for the apparatus comprising: a thin-walled cover bodyformed of electrically insulative material, said cover body having anupper surface and an integral wall segment extending away from anddiscontinuously about the periphery of the surface; said body includingmeans for receiving a demountable receptacle plate in an alignedposition; a generally flat, thin-walled, demountable electricalreceptacle mounting plate positioned in alignment with said cover bodyand forming with said wall segment a continuous four-sided wall for theapparatus, one side formed by said receptacle plate and a side oppositesaid receptacle plate including an aperture for receiving a power supplycable; a generally flat, thin-walled electrically insulative base meansformed of at least two generally flat members for supporting said bodyon a surface and for forming with said body an enclosure for componentsof a circuit arrangement for the apparatus; and a plurality of flatcircuit boards formed of electrically insulative material supportedwithin said housing in a direction parallel to said receptacle plate bymembers integrally molded in said cover body and forming with said coverbody, said receptacle plate and said base means a plurality ofcompartments, one of said flat support plate members forming a closurefor one of said plurality of compartments formed by one of said circuitboards and said wall segment including said apertured side.
 2. Theapparatus of claim 1 wherein said one of said circuit boards includes aplurality of feed-through terminals for receiving conductors of a powercable.
 3. The apparatus of claim 1 including an electrical power supplyinput cable clamp comprising first and second semicircular segmentshaving a plurality of semicircular ribs adapted to grip an electricalpower supply input cable transversely at a plurality of axially spacedpoints and said first segment is integrally molded in said cover body orbase means.
 4. ThE apparatus of claim 3 wherein said integrally moldedsegment is molded in said cover body.
 5. The apparatus of claim 1wherein said receptacle plate includes a plurality of receptacleapertures, a plurality of receptacles mounted thereto at associatedapertures by electrically conductive means, and a thin-walled insulativebody positioned at an outer exposed surface of the plate and bondedthereto near each of said receptacle apertures.
 6. The apparatus ofclaim 1 wherein said receptacle plate is positioned in a plane inclinedwith respect to said base means and includes a plurality of receptaclesmounted thereon, all of said receptacles being aligned in a singledirection on said plate.
 7. The apparatus of claim 6 wherein saidreceptacle plate includes tapered flanges at opposite extremitiesthereof and a tongue segment at one edge thereof, said cover bodyincludes integrally molded tapered grooves for receiving said flangesand said base means includes a groove for receiving said tongue segmentfor securing said receptacle plate.
 8. The apparatus of claim 1including a two-piece transport handle, said handle comprising a firstmember integrally molded to said cover body, said molded handle memberhaving a pair of segments extending generally normally away from saidwall and a transverse segment extending between said normal segments,and an elongated gripping member positioned on said transverse segment.9. The apparatus of claim 8 wherein said transverse handle segment has across section which is generally arrow-shaped and said gripping memberincludes a groove having a cross section formed for receiving saidarrow-shaped transverse segment.
 10. The apparatus of claim 6 includinga flat, linear, elongated ground bar of generally rectangular crosssection which is formed of an electrically conductive material, said barincluding a plurality of slots formed in the cross section along itslength for receiving a grounding screw of a receptacle to therebyprovide a common grounding bar for a plurality of receptacles, saidground bar including a flanged segment at an extremity thereof, therebyforming a male terminal for engaging a female connector.
 11. In anelectrical apparatus for interrupting the coupling of electrical powerbetween a source of power and a utility device upon the occurrence of afault in a ground circuit, an improved portable housing arrangement forthe apparatus comprising; a thin-walled cover body formed ofelectrically insulative material, said cover body having an uppersurface and an integral wall segment extending away from anddiscontinuously about the periphery of the surface; said body includingmeans for receiving a demountable receptacle plate in an alignedposition; a generally flat, thin-walled, demountable electricalreceptacle mounting plate positioned in alignment with said cover bodyand forming with said wall segment a continuous wall for the apparatus;a generally flat, thin-walled electrically insulative base means forsupporting said body on a surface and for forming with said body anenclosure for components of a circuit arrangement for the apparatus;said cover body including a plurality of linear, elongated, integrallymolded bosses extending from the upper surface in a direction generallyperpendicular to said upper surface and for a distance substantiallyequal to a width of said wall, said bosses including recesses formedtherein for receiving a mounting member, and said base means includesapertures formed therein through which a mounting member extends forsecuring said base means to said cover body; and circuit mounting meanssupported within said housing and forming with said cover body, saidreceptacle plate and said base means a plurality of compartments. 12.The apparatus of claim 11 including an apertured cap of electricallyconductive material positioned on an extremity of said boss forintroducing a mounting member to the recess of said boss, and anintegrallY molded skirt formed in said insulative support base means,co-aligned with said boss, and extending a distance away from saidsupport base means for shielding said cap.